The purpose of this prospective study is to determine whether DNA content of tumor cells, measured by flow cytometry is an independent prognostic variable in colonic carcinomas surgically resected for cure. In selected cases flow cytometric data will be compared with Feulgen cytophotometry. The significance of DNA ploidy and cell cycle kinetics will be assessed by multivariate statistical analysis of factors, such as age, sex, tumor location, size, stage (Dukes'), grade (histology), CEA levels, and the presence of peripheral polyps in reference to recurrence, metastases and 5-year disease-free survival. The cohort of over 300 patients entered into the study during the first 3 years of this research will be followed and enlarged to 500 patients, needed to provide a sound statistical basis for the analysis, as discussed in the Research Plan. Preliminary evaluation of 274 patients is described. Cell cycle kinetics which have been calculated on 188 benign control colonic samples will be extended to tumor samples in all cases entered into the study. A comparison of flow cytometic results with 3H thymidine uptake should provide additional data on tumor cells in S phase, to be differentiated from non-replicating tumor cells with DNA content in the same range. The significance of variable DNA ploidy in multiple samples of the primary tumors will be examined. We also will compare the measurements of DNA ploidy in fresh material with that of formalin fixed and paraffin embedded tissues. Using the method of Hedley we will specifically examine the effect of duration of storage on DNA patterns in tissue blocks, 1, 2 or more years old. This comparison will be conducted on 200 cases of colon cancer in which fresh material was examined within the past 5 years and on a available paraffin blocks of tumor. Because of increasing interest in processing material from paraffin blocks in cases with known clinical outcome, this comparison will be important to determine the validity and clinical value of DNA determinations in such studies. If DNA ploidy proves to be a factor of prognostic value, as suggested in preliminary studies by us and others, this observation may have significant clinical implications, particularly for the common categories of colon cancers Dukes' stage B and C and histologic grade II.